Field of the Invention
Embodiments of the present invention relate to a printed circuit board having an electronic component which generates heat and an electronic apparatus including the printed circuit board.
Description of the Related Art
In order to avoid performance degradation due to temperature increases, countermeasures against heat may be required in an electronic component which generates heat, such as a driver IC configured to drive a motor. As such countermeasures against heat, an increased number of electronic components have a heat radiation pad (heat sink) in recent years.
The heat generated from such an electronic component is conducted from a heat radiation pad of the electronic component through a conductive jointing material of solder, for example, to heat radiation lands on a printed wiring board. The heat conducted to the heat radiation lands is then conducted to a plane-shaped conductor pattern on an opposite surface of a surface having an electronic component or in an inner layer through a via conductor placed in the heat radiation lands and is dissipated into the air. When the heat radiation only with such a conductor pattern is not sufficient, countermeasures against heat are provided such as attaching a heat sink thereto. On the other hand, because of increased needs for downsizing and cost reduction of products, it has been desired not only to refrain from use of a heat sink but also to reduce the size of the printed circuit board.
Accordingly, a technology has been proposed (as in Japanese Patent No. 4396005) in the past which includes a circuit component different from an electronic component on the opposite surface of a surface having the electronic component thereon so that heat generated from the electronic component is absorbed by the circuit component and is dissipated from the circuit component, without using a heat sink.
However, in a case where a plurality of electronic components which generate heat is mounted on a printed wiring board, thermal interference may occur among the plurality of electronic components. For example, in a case where two electronic components having different heat values from each other are mounted on a printed wiring board, one having a higher heat value of the electronic components is influenced by heat generated from the other electronic component. As a result, the heat radiation is prevented, and the temperature increases. In order to reduce the increase in temperature, increasing the area of the conductor pattern thermally connected to the heat radiation pad may disadvantageously increase the size of the printed circuit board.